The present invention relates to aromatization reactions with zeolites, such as ZSM-5, containing an oxide of phosphorus.
The Chester et al U.S. Pat. No. 4,350,835 describes a process for converting ethane to liquid aromatics by contacting the ethane with a zeolite catalyst such as ZSM-5 having incorporated therein a minor amount of gallium.
The Davies et al U.S. Pat. No. 4,175,057 describes a process for producing aromatics by contacting a C.sub.3 -C.sub.8 hydrocarbon with a gallium catalyst supported on an aluminosilicate in which the ratio of silica to alumina is between 20:1 and 70:1.
The Bulford et al U.S. Pat. No. 4,157,356 describes a process for producing aromatic hydrocarbons by contacting a C.sub.3 -C.sub.8 hydrocarbon with a gallium catalyst on a silica support which has a surface area greater than 500 m.sup.2 /g and a pore volume less than 0.8 ml/g.
The Butter et al U.S. Pat. No 3,972,832 and the Kaeding et al U.S. Pat. No. 3,911,041 describe the treatment of various zeolites with phosphorus compounds which are capable of reacting or exchanging with hydrogen in zeolites followed by calcination. This particular phosphorus treatment is taught to result in the substantial reduction of aromatization activity of the zeolites. For example, note column 6, line 59 to column 7, line 13 of the Butter et al patent and column 7, lines 34-57 of the Kaeding et al patent.
The entire disclosures of the above-mentioned U.S. Patents are expressly incorporated herein by reference.